kill-stale-client did `pkill -f ps5upload-engine`, which SIGTERMed
every engine on the machine — a standalone one on another port died 70
minutes into a package build. It now stops only an engine listening on
19113 (an engine whose app is gone exits by itself). The decision is a
small pure module with node:test cases, which scripts:check now runs.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
